linux-kernel - Re: [PATCH v2 0/5] remove runnable_load_avg and improve group

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Message-ID: <827f745e-5afc-88b1-0a93-b5d2dfd796db@arm.com>
Date:   Fri, 21 Feb 2020 10:58:05 +0100
From:   Dietmar Eggemann <dietmar.eggemann@....com>
To:     Vincent Guittot <vincent.guittot@...aro.org>, mingo@...hat.com,
        peterz@...radead.org, juri.lelli@...hat.com, rostedt@...dmis.org,
        bsegall@...gle.com, mgorman@...e.de, linux-kernel@...r.kernel.org
Cc:     pauld@...hat.com, parth@...ux.ibm.com, valentin.schneider@....com,
        hdanton@...a.com
Subject: Re: [PATCH v2 0/5] remove runnable_load_avg and improve
 group_classify

On 14/02/2020 16:27, Vincent Guittot wrote:
> This new version stays quite close to the previous one and should 
> replace without problems the previous one that part of Mel's patchset:
> https://lkml.org/lkml/2020/2/14/156
> 
> NUMA load balancing is the last remaining piece of code that uses the 
> runnable_load_avg of PELT to balance tasks between nodes. The normal
> load_balance has replaced it by a better description of the current state
> of the group of cpus.  The same policy can be applied to the numa
> balancing.
> 
> Once unused, runnable_load_avg can be replaced by a simpler runnable_avg
> signal that tracks the waiting time of tasks on rq. Currently, the state
> of a group of CPUs is defined thanks to the number of running task and the
> level of utilization of rq. But the utilization can be temporarly low
> after the migration of a task whereas the rq is still overloaded with
> tasks. In such case where tasks were competing for the rq, the
> runnable_avg will stay high after the migration.

With those small things I commented on:

Reviewed-by: "Dietmar Eggemann <dietmar.eggemann@....com>"